In critical care and home care health service centers including hospitals, clinics, assisted living centers and the like, caregiver-patient interaction time is at a premium. Caregivers are needed to respond rapidly to significant health conditions because any delay can be the difference between life and death. Systems of centralized monitoring have been developed to assist caregivers by transmitting physiological data from each patient (or from geographically-dispersed critical care health service centers) to a centralized location.
At this centralized location, a single or small number of technicians monitor all of this patient information to determine patient status. Information indicating a patient alarm condition will prompt the technicians and/or system to communicate with caregivers to provide immediate patient attention, for example via wireless pagers and/or cell phones, and/or by making a facility-wide audio page.
The information transmitted to the centralized location could be performed over a local area network, such as with a “WiFi” network based on IEEE 802.11 standards. The problem, however, with this network is that it is often difficult to secure sufficient local area network access for the purpose of providing centralized monitoring. Moreover, when a patient is located remotely from a critical care health service center (e.g., at home), access to traditional local area network facilities such as a WiFi network may be unavailable or not sufficiently reliable to support critical care monitoring applications.
An alternative to using WiFi is ZIGBEE, based on the IEEE 802.15.4 standard for wireless personal area networks. The ZIGBEE networks have previously been used for collecting information from a variety of medical devices in accordance with IEEE 11073 Device Specializations standard for point-of-care medical device communication, include for example pulse oximeters, blood pressure monitors, pulse monitors, weight scales and glucose meters. See, e.g., ZIGBEE Wireless Sensor Applications for Health, Wellness and Fitness, the ZIGBEE Alliance, March 2009, which is incorporated by reference herein in its entirety for all purposes.
The advantages of ZIGBEE networks are that the network is dynamically configurable (e.g., “self-healing” mesh configurations) and operates with low power requirements (e.g., enabling ZIGBEE transceivers to be integrally coupled to the medical devices under battery power). In addition, ZIGBEE networks generally require shorter, less cumbersome passwords for secure network access that are used for securely accessing WiFi networks (for example, the wired equivalent privacy or “WEP” passwords used in WiFi networks. However, transmission ranges between individual ZIGBEE transceivers are generally limited to no more than several hundred feet. As a consequence, ZIGBEE networks are generally unusable for centralized monitoring locations located off-site, or for conditions in which a patient may be ambulatory and the distance between a medical device with a ZIGBEE transmitter and the ZIGBEE receiver may vary and at times extend beyond several hundred feet.
The remote monitoring system may be provided with an intermediate device (wireless relay module) that receives medical device data from a medical device via a WiFi or ZIGBEE network, and that relays this information to the centralized location via an internet-accessible wide area network (WAN) such as a cellular network.